Various metalization, interconnect, and polycide formation processes are known and used in the fabrication of semiconductor devices. In the fabrication of many of such semiconductor devices, a conductive material such as titanium is used, for example, to form an ohmic contact to a silicon substrate. For example, in accordance with a conventional salicide or silicide fabrication process, titanium is often deposited on a semiconductor device structure which includes a silicon surface, e.g., contact area, and a silicon dioxide surface, e.g., field oxide surface. After forming a titanium layer on the silicon surface and silicon dioxide surface, the device structure may be subjected to a high temperature anneal, so as to form titanium suicide in the region where the titanium contacts the silicon surface and/or titanium nitride over portions of the structure.
In accordance with such a conventional fabrication approach, titanium oxide is likely to form at an interface between the titanium and silicon dioxide regions. During silicidation and/or salicidation processes, this interfacial titanium oxide formation can adversely affect the operational and reliability characteristics of the subject semiconductor device, such as by increasing contact resistance within the device and/or by encroaching into the active area of a circuit structure being formed. Undesirable titanium oxide formation may also adversely affect the thermal stability of the subject semiconductor device. The formation of interfacial titanium oxide during the fabrication of a titanium nitride local interconnect results in similar reliability and operational anomalies in the subject semiconductor device.
Further complicating known processes that utilize titanium in the fabrication of semiconductor device structures is the difficulty of removing titanium oxide within the device structure during conventional processing. By way of example, and in accordance with a conventional salicidation process, titanium oxide is generally not removed with use of traditional etching or cleaning techniques, during which undesired material such as titanium nitride or unreacted titanium is removed leaving titanium silicide as an ohmic contact to the silicon substrate.